Rubber strap



FIG. 1 is a perspective view of a rubber strap;

FIG. 2 is a top plan thereof;

FIG. 3 is a bottom plan view thereof; and,

FIG. 4 is left side elevational view thereof.

The broken lines illustrate environment only; the broken lines form no part of the claimed design. 

We claim the ornamental design for a rubber strap, as shown and described. 